Inspection and measurement devices detect abnormalities based on a set of predetermined standards, or are used in tasks to indicate by numerical value the length, weight, volume, etc., of an object or a phenomena. An example of such devices is an oscilloscope, which is used to provide a visual representation of sound waves. Commonly, Inspection and measurement devices can detect high-frequency signals and are used in electrical testing. Inspection and measurement devices also include electrical current and voltage testers. They come in either digital or analog types and are available in thin card-like designs, pencil-type designs, etc. Other instruments include vernier calipers used for measuring parts of objects, scales for measuring the length, weight, angle, etc., of objects, etc.